Need for Washer Flexibility in a Recycled Fiber System, 1998 Recycling Symposium Proceedings

Washers are pieces of equipment that work well under steady state conditions. Recycled fiber mill startups are by no means classified as steady state operations, and the need for a washer to cover all aspects of startup is essential to the overall fine-tuning of the system in its startup phase. An impingement feed washer was chosen for this recycled fiber system and its versatility was called upon many times.

The flexibility required during mill startup included turndown tonnage operation; efficient washing of contaminants such as inks, ash and stickies; yield control; sludge system fiber reduction; and final product freeness control. Each situation was handled successfully by the washer. The results achieved showed a washer yield improvement of 55% which resulted from changes to the washer system. Freeness was decreased by 90 CSF with an increase of only 0.2% ash by changing the method of washer feed. Filtrate losses were reduced by 20% by making other on-the-fly changes to the washer when it was operated at low consistency.